This invention relates to vehicular disc brakes of the sliding caliper type and, more particularly, to a caliper guide assembly for a sliding caliper disc brake.
In a typical sliding caliper disc brake, the caliper embraces the disc and is slideably supported at its opposite end by a torque plate fixedly secured to a non-rotating portion of the axle assembly of the associated vehicle. As the brake is applied by the actuator assembly, the brake pad driven directly by the actuator assembly, typically the inboard pad, is pressed against the inboard face of the disc, whereafter, with continued driving input from the actuator assembly, the caliper slides inboard on the torque plate to bring the outboard pad, carried by the caliper, into frictional engagement with the outboard face of the disc. The guide means for slideably mounting the caliper on the torque plate is a critical design ingredient in any sliding caliper disc brake. The guide means must be inexpensive to manufacture. It must fit within a very restricted space. It must in many cases efficiently transmit the braking forces to the torque plate. It must itself be virtually maintenance free; and must provide ready removal, and replacement, of the caliper for purposes of servicing the brake elements associated with the caliper. And it must provide a smooth, low friction slideway for the caliper over the entire life of the brake.
Most prior art guide means have involved the use of a pair of guide pins which, in door hinge fashion, pass through aligned holes in the torque plate and in the caliper to retain the caliper on the torque plate while allowing the caliper to slide axially on the guide pins. This guide means design, while broadly satisfactory in general application, has several disadvantages. Specifically, this design tends to be rather intricate and therefore expensive to manufacture. This design also requires axial withdrawal of the pins to accomplish removal of the caliper for servicing--a procedure that can be quite awkward, especially in heavy duty truck applications where adjacent equipment severely encroaches on the space available around the brake. These hinge type pins--and the holes through which they pass--also tend to plug up and corrode, thereby impeding the smooth sliding movement of the caliper during the braking operation and requiring a periodic maintenance operation and expense directly predicated on the guide means design. Various other guide means designs have been proposed in an attempt to eliminate or diminish the described disadvantages of the hinge type design. However, these other designs, broadly considered, have achieved diminution of the disadvantages of the hinge type design only at the expense of generating other disadvantages such, for example, as increased complexity, increased manufacturing cost, decreased effectiveness in transmitting the braking forces to the torque plate, and increased resistance to the sliding movement of the caliper.